1. Field of the Invention
The present invention relates to a method and a system for transmitting and receiving a signal in a mobile communication system provided with a plurality of antennas.
2. Discussion of the Related Art
Generally, in the 3rd generation and the following wireless communication systems has been used a high-performance channel coding technique using a convolutional code, a turbo code, etc., to maintain a high quality of a transmitted signal. This channel coding technique is for protecting information through a process of inserting redundant check bits into information bits.
Meanwhile, diverse space-time coding techniques for obtaining a transmission diversity using a multi-antenna transmission system have recently appeared. Especially, in a system that uses multiple antennas, researches have been actively made for a layer type space-time coding system for separating information to be transmitted into a plurality of layers and encoding the separated layers in order to simultaneously obtain a channel coding and transmission antenna diversity.
FIG. 1 shows an example of the construction of a conventional transmitter using space-time encoders. FIG. 2 shows another example of the construction of a conventional transmitter using space-time encoders.
Referring to FIGS. 1 and 2, encoding of input data is performed twice through two kinds of encoders 101, 103, 202, and 204 provided in front and rear of interleavers 102 and 203. This encoding process is performed for respective layers to generate signals to be transmitted through a plurality of modulators 104 and 205 to a plurality of antennas. A demultiplexer 201 receives input data and outputs the data to a plurality of encoders 202. A part of encoders 101 and 202 use a channel error correction code such as a convolutional code and so on. The space-time encoders 103 and 204 use an orthogonal code and so on that can increase the independence among the antennas.
The two kinds of encoders (i.e., the encoders and the space-time encoders) used in the above process are independently constructed. This causes decoders for twice decoding in a receiving end to separately operate without exchanging information with each other. That is, the iterative decoding process is not performed.
As described above, according to the conventional multi-antenna transmission system, the channel coding and the space-time code system of the respective layer are not combined with those of other layers, but are independently combined in the corresponding layer only. Thus, the conventional system has the limitations that it cannot obtain an ascending effect through combination of a channel decoder and space diversity by layers.
Also, the members of the next-generation mobile communication system such as the 3GPP for developing the recent 3rd generation mobile communication system, adapts the turbo code as a standard, and a diversity structure that performs transmission using two antennas. However, even in this system, the turbo code and the transmission diversity system independently exist without correlation between them, and thus the additional gain through the combination of the two systems cannot be obtained.